Got a Great Windshield-Whoah! Bad ass suction!

[Anonymous]

I got a windscreen off of ebay. It is a National cycle plexiglass fairing 3. Basically it is the largest windshield you can buy. You see, I want to ride all year long out here in Portland, Oregon. So after getting this thing on, I cruise down the highway and notice that- Hey! I am being pushed towards the handlebars. What is figure is happening is this: The wind is being deflected over the top of the screen and then being pushed down right on to my head. Because of the fact that my helmet is round, it feels that I am being pushed foward. How can I resolve this. It has been suggested that I angle the screen towards me, thus moving the windstream back towards the rear of the bike. That is not possible without major modifications because of the stock signals. It also has been suggested to drill 3"(inch) holes in the front to allow air in. This way, the negative air pressure is alleviated. So, all you physics majors and/or people that have this issue, please helo me out. Also, I notice that if my head is above the shield by 6 inches, the problem is alleviated, but then again, my face is into the wind, but hey nothing is perfect. Thanks,
Chris

[earlfor]

Any object moving through the air will have a low pressure area following it. It is why you can "draft" a tractor trailer rig. The low pressure area pulls the bike along. For your windshield, apparently your helmet is in the low pressure area. It usually does not take much to alter the pressure distribution. For a relationship such as the size of a windshield and a helmet, It may be sufficient to take a piece of clear vinyl tubing with a 1/4" I.D and lengthwise slit a 12" piece of it, Press this on the top edge of the windshield as an edge cap and it will give a turbulent flow coming off the windshield edge. That will relocate the low pressure zone.
If this isnt enough, making a small cut in the top of the windshield in a couple places and reforming the edge with a heat gun so that it resembles an upturned flap will definately relocate the problem area.

Earl

[Anonymous]

I actaully enjoyed that windshield draft.
As far as adjusting your shield... What type is it? You shold be able to adjust the top of it. I had a four point bracing system. I was able to adjust the top two mounts. That would allow the top of the windshield to move about 2". Check your clamps/mounts again.

[Anonymous]

Thanks for the advice

Thanks for the advice. I will try that. Right now the seat that I have is junk. It sits fairly low. I am attempting to locate another seat that is better made. After I do, I will try the tube idea. What do you think of putting the holes in the windshield? Also, no, I can not adjust the windshield due to the 5 foot turn signals on each side of the bike.
Go suzuki. Maybe I can find something smaller. Here is a picture of it.

http://cgi.ebay.com/ebaymotors/ws/eB...860259187&rd=1[/url]

[Anonymous]

Hi Chris,

The best way of getting rid of the draft and turbulence is cutting a slot in the bottom of the windscreen. Take a look at the screens that BMW puts on their bikes these days, there is a post box size slot in the lower edge.

This has the effect of allowing a controlled amount of air in behind the screen and preventing the low pressure area. If you do it right it will also cause that air to move up the inside of the screen and join the main flow coming over the top so you don't get any flow against your body.

Take a look at the home made mini screen on my GS1000G here

http://users.tpg.com.au/kkmiller/bike/GS1000G.htm

Just that small screen, with a bit of experimenting to get the right size air slot across the front, gets rid of the high turbulence that the original bubble screen produced.

Kim

[Anonymous]

THE HOME MADE SREEN

[Anonymous]

That's the EXACT fairing that I had. National Cycle right?! Check out my windshield in the gallery. I'll even send you a copy of the pic. Turn the clamps on the bottom so that the mounts give you clearance. Then loosen the nuts on top so that the posts will move. I'm not sure why the turn signals are keeping you from adjusting your shield

Before you cut holes in it, try sliding it up. This should allow more air flow into your chest area from over the headlight. I really would hate to see you distroy that fairing with holes. If I'm doing this right, this should be my avatar:

[img]

The mounting brackets... Are they hose clamps, that hold on a mount to the fork (bottom)? The black mounts should be clamped to the outside of the forks, slightly rearward. The metal bars that attach to the plexi should be able to reach the mount just about where ever you put it. If you don't have the original mounts, I have mine that I can give you. I kept them after trashing my windshield (just in case).

[Anonymous]

thats Kim millers bike not Chris's bike--i couldnt make the link to the yahoo page work unless you are referring to the photo at this site--this is the windshield that motorpig has http://www.geocities.com/slowpoke59d...aryPhotos.html

[Anonymous]

Yes, I know. Chris has the tall windshield. Just like the one on my bike in the gallery.

[Anonymous]

Bernoulli effect, for all you physics geeks out there

[Anonymous]

Thanks for all the info, but please, it's Meterpig.

I rode the bike today. I am getting more used to it. I think that I will put the stock handlebars on and track down a seat and then see where I am at.

[Anonymous]

Kim:
What the heck are those goofy looking racks you Austrailians have on the backs of your bikes? I was ready the following story and he had one too.

http://www.horizonsunlimited.com/tstories/heath1.shtml

Steve

[Anonymous]

My 1983 GS1100E came equiped with one of those "goofy racks". I keep it in the garage but when i go on an over nighter or longer the rack serves me well--I can hang my sadle bags on it and i bungie my back pack to it also. Then i love the thing..this is my bike with the rack.. Is this the same as the one on the photo?? It looks to be>

http://www.geocities.com/slowpoke59ds/MyNewMainPage.html

[Anonymous]

Kim:
What the heck are those goofy looking racks you Austrailians have on the backs of your bikes? I was ready the following story and he had one too.

http://www.horizonsunlimited.com/tstories/heath1.shtml

Steve

That's a Gearsack rack. Gearsack is a popular Australian brand of soft bike luggage. Here's a link, just hit the gearsack logo to see what they make. This stuff is well made and the pack can sit to the front over the pillion seat so other stuff can strap to the rack, or the pack can sit facing backwards if I have a pillion.

http://www.ronangel.com.au/product.htm

Kim